Time-shaped lamp control apparatus employing lamp filament resistance as an integral status memory

ABSTRACT

Time sharing techniques are applied to control the operation of a plurality of lamps which report operational conditions of the system in which they are employed. The lamps, which may be physically located in separate groups, are electrically connected in a matrix along coordinates of lamp location and system operational condition (function reported). The hot or cold filament resistance of each lamp, which serves as an integral status memory, is sampled by time-sharing circuits which determine and maintain the sampled status of a lamp. Circuits are also provided for altering the ON-OFF condition of any lamp in response to a corresponding change in system operational condition.

United States Patent TIME-SHARED LAMP COSTROL APPARATUS EMPLOYING LAMPFILAMENT RESISTANCE AS AN INTEGRAL STATUS MEMORY 2 Claims, 5 DrawingFigs.

US. Cl ..3-10/173 LT.

Int. Cl G1 1c 5/02, G1 10 11/42 340/173,

FieldoiSearch v 166 FUNCTION *1 Primary Examiner-Terrell W. FearsAssistant Examiner-Stuart Hecker AttorneysSpencer E. Olson, K.Mullerheim and B. E. Franz ABSTRACT: Time sharing techniques are appliedto control the operation of a plurality of lamps which reportoperational conditions of the system in which they are employed. Thelamps, which may be physically located in separate groups, areelectrically connected in a matrix along coordinates of lamp locationand system operational condition (function reported) The hot or coldfilament resistance of each lamp, which serves as an integral statusmemory, is sampled by timesharing circuits which determine and maintainthe sampled status of a lamp. Circuits are also provided for alteringthe ON-OFF condition of any lamp in response to a corresponding changein system operational condition.

FUNCTION 12 FUNCTION n DATA CHANNEL 80 FROM DATA SYSTEM- -VlNTERROGATlO-v CIRCUIT LATCH ClRCUlT DATA iNPUT CIRCUIT LATCH (RESET)CONTROL CCT.

LATCH ClRCUIT DATA CHANNEL SHEET 1 UF 3 DATA SYSTEM CONTROL CHANNELCONTROL 3 IN mozo-uwm -Ico:0o

LOCATION 1 LOOATION**2 8| k. TIMING CIRCUITS Q LAMP STATUS SAMPLER 5}DRIVERS 2. DATA k, W SUBCHANNEL INTERROGATION e3 OIROUITQQ LATCH CONTROLCIRCUIT i1 REGISTER ii. DECODER LOcATION**3 LAMP MATRIX IO LOOATION**k-2I OcATION**k OATA INPUT CIRCUIT FIG.

LAMP CONNECTION CONTROL CIRCUITS TTY.

PATENTED JUN22 |s7| SHEET 2 OF 3 PATENTEUJUNZZISYI 3v, M1061 sum 3 or 3HORIZONTAL CONDUCTOR I31 n 14 2 I-gfiZ HORIZONTAL CONDUCTOR I32 m kHORIZONTAL CONDUCTOR I3k I I2 I3 I I1 I2 M JIL UL CONDUCTOR 35 (SAMPLINGCONTROL) W-----W CONDUCTOR 53 (RESET CONTROLI k 1 '2 rIk-l) r r r I IWRITE 1' (ON) INPUT FROM I l DECODER 62 TO LATCH CCT. 40

' F" Fn I mfinflw WRITE0 (OFF) INPUT FROM DECODER 62 TO LATCH CCT. 40n

FIG. 3

LAMP CURRENT TIME 7 FIG 4 LAMP I RESISTANCE (OHMS) TYPE. 32a

I I l I 7 1 2 3 4 5 6 TIME (SEC) 5 TIME-SHARED LAMP CONTROL APPARATUS VEMlPLOYllNG LAMP FILAMENT RESISTANCE AS AN INTEGRAL STATUS MEMORYBACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to apparatus for controlling the operation of a plurality ofindicating lamps, and particularly to apparatus for controlling theoperation of such lamps on a time-sharing basis in response to thethermal condition of the lamp filaments or in response to an externaldata input.

2. Prior Art Indicating lamps have long been used to report theoperational conditions of various types of systems including telephone,computer and supervisory control systems. Such applications have usuallybeen operated on a digital control basis wherein a lamp is conditionedeither ON or OFF as the result of a lamp driving circuit beingcorrespondingly operated and maintained in its state of operation inresponse to a combination or controlling conditions. As systems grew andbegan requiring increasing numbers of function indicating lamps, thecost of the attendant logic and driving apparatus began to increase withrespect to overall system cost. The application of time-sharingtechniques on a more or less limited scale has tended to improve theabove cost factor; however, the requirement for a lamp status memory andits associated accessing circuits is disadvantageous from thestandpoints of cost, additional hardware and software provisions andmaintenance programs and techniques.

SUMMARY OF THE INVENTION Briefly, and in contrast to the above-describedtime-sharing approach, the present invention employs a minimum of theadditional equipment and techniques set forth above, holds cost to aminimum and simplifies maintenance. Inasmuch as an incandescent lamp mayexhibit a marked degree of dif ference between its hot and cold filamentresistance, this thermoelectric property is advantageously utilized fordetermining lamp status and for maintaining that status. For reportingthe conditions of a system wherein function lamps at one locationcorrespond to function lamps at another location which report similarsystem conditions, all such lamps are advantageously connected in amatrix and time sharing is employed for sampling and driving all lampsof the matrix. The time-sharing circuits are also employed toselectively alter lamp status in response to input signals whichindicate changes in system operational conditions. A plurality ofoperator's consoles, for example, which are all constructed the same andwhich report the same type of information for different circuits, mayadvantageously employ the time-shared circuits of this inventron.

From the above, it is evident that the primary purpose of this inventionis to provide improved operational control of large numbers of lamps(although the invention is equally applicable to small numbers of lamps)by providing a new lamp control subsystem for reporting the operationalconditions of a system. Such a subsystem will find application in anytype of system which requires condition reporting, and is particularlyapplicable to systems which have a plurality of operator consoles, suchas computer and telephone systems.

BRIEF DESCRIPTION OF THE DRAWINGS The invention, its organization,construction and operation, will be best understood from a reading ofthe description below in conjunction with reference to the accompanyingdrawings, in which:

FIG. l is a block diagram of a system which incorporates the presentinvention;

FIG. 2 is a partial schematic, partial block diagram showing theembodiment of FIG. 1 in greater detail;

FIG. 3 illustrates the relationships between the time division driving,sampling, resetting and writing pulses as applied to the embodimentshown in FIG. 2;

FIG. 4 illustrates the current of a lamp tested for utilization in thepresent invention; and

FIG. 5 shows the cooling characteristic of a similar lamp tested forutilization in the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. I illustrates an embodimentof the invention incorporated in a data or switching system having aplurality of GO/NO-GO (ON-OFF, true-false) operational circuits ll,l,which are assigned to report their operational status to lamps atLOCATIONS Ill-0k of lamp matrix by assignor 2 under the control of thedata system control 3 via control channel 4. The condition of theoperational circuits (symbolized by switches) may be controlled many ofseveral well known ways (e.g. data conditions of system control 3,operator-controlled switches, etc.) and is only generally discussedherein in terms of result, in that the operational circuits report theirchange of condition to the system control 3. The remainder of FIG. Iillustrates the time-sharing circuits comprising: lamp status samplingcircuit 5, lamp connection control circuits 40, latch and reset controlcircuit 50, data input circuit 60 including register 61 and decoder 62,and timing circuits 70 which control the sequence of operation of thetime-shared circuits. The timing circuits may be self-regulated, or theymay be synchronized to total system timing, as indicated by connection81 of the data channel 80.

FIG. 2 illustrates the above embodiment of the present invention in moredetail as comprising a lamp matrix 10 having connected to one sidethereof a distributor 25 and to another side thereof an interrogationcircuit, elements 30-35, and latch circuits 40. The interrogationcircuit is connected to the subsystem timing circuits 70; the latchcircuits also being connected to the timing circuits via a latch (orreset) control circuit 50 and to the data input circuits 60.

More specifically, the lamp matrix 10 comprises indicating lamps II1ll,, connected between location conductors i13,13,, and functionconductors l4,l4,, via sneak path preventing diodes l2 -12,, The brokenlines about the lamps symbolize that although each horizontal row oflamps (LOCATION (Ill-LOCATION 0k) may be remotely located from the otherhorizontal row of lamps, each lamp of a vertical row (FUNCTION(II-FUNCTION 0n) reports (for a separate circuit) the same type ofsystem function as the other lamps in that row report to theirrespective physical location, which locations may be operator consoles.Of course, if condition reports are not necessary for all functions atall consoles, the corresponding function lamp may be omitted, asillustrated at matrix coordinates LOCATION 0k, FUNCTION 02. Any desiredoperational circuit-lamp-location association may be employed inpracticing the present invention. For example, it is not necessary foreach lamp of a vertical row to report the same type of function. Thisflexible arrangement is affected by the present embodiment wherein theinvention is shown as applied to the control the lamps at a plurality ofgenerally similar operators consoles. Also, it is not necessary that thelamps be placed in a matrix. It will be apparent from the descriptionbelow that a single column of lamps, such as any function columnillustrated in FIG. 2, could employ the teachings of the presentinvention. A

The time-sharing drivers are connected between the distributor 25 andcorresponding location conductors 13 -13,, of the matrix. These driversinclude transistors 20 -20, having their collectors connected to sourcepotential V via resistors ZI -21 and their emitters connected to groundpotential.

The interrogation circuit which forms one portion of the time-sharingequipment comprises a transistor 30 having its emitter connected tosource potential V and its collector connected to each of the functionconductors 14,--14,, by

way of conductor 33, diodes 32,32,, and resistors 31,-31, and to groundpotential via resistor 34.

Another portion of the time-sharing equipment, the latch and resetcircuits, comprises a normally conductive transistor 50 having agrounded emitter electrode and having its collector connected to V viaresistor 52 and to each of the n latch circuits 40,-40,,. Referring tolatch circuit 40,, transistors 41 and 42 are normally biasednonconductive via resistors 43 and 44, ground potential at the emitterof transistors 41 (via diode 46) and 42, by the condition of the decoder62. Each of the latch circuits is connected to a corresponding functionbus of the matrix for sensing lamp status and for maintaining lampstatus.

The matrix is controlled by a distributor 25 and timing circuits 70which may be similar to the time division power supply disclosed by R.M. Schildgen and John S. Young in their US. Pat. No. 3,328,530 entitled"Director System with Time Division Access of a Common Translator." Thematrix is further controlled by register and decoder circuits 61-62.These control circuits may take the form of circuits which are wellknown in the art, and as they form a part of the present invention onlyas employed with a lamp matrix, they will not be discussed in circuitdetail, but only by circuit function.

FIG. 3 is fairly self-explanatory showing the pulses of the subsystem ofFIG. 2. Pulses 0,0,, are repetitively applied to conductors 13,13respectively, upon the sequential operation of transistors 20,20,, bythe distributor 25. Pulses i,--i,, are the control pulses for operatingthe interrogation transistors 30 for sampling lamp conditions and pulsesr, r,, are the reset control pulses applied to the latch circuits fromtransistor 50. The small marks preceding an interrogation control pulseindicate the beginning of the time positions. Pulses 0,F2, and 0,Fn arewriting pulses which are applied to the latch circuits by the decoder 62in order to alter the status of lamps in the specific example given inthe operational description below.

FIG. 4 shows the results of test driving a Type 47, 6 volt incandescentlamp with 44 volts for a time position (1,) of 200 microseconds and anOFF time (1,) of 10 milliseconds, although a frame of 6.4 millisecondswith 100 microsecond time positions is expected to be used for a 64location system using Type 328 lamps at 48 volts. It can be seen thatthe current decreases rapidly as the lamp heats for illumination.Typically, the resistance of the lamps tested changes approximatelyeight to ten times over a temperature range between their dark and fullylighted states. FIG. shows the cooling characteristics of a Type 328lamp as compared to the plot of a 350 millisecond time constant (smoothbroken line). From tests such as the above, and from visual tests, ithas been determined that in the resistance (temperature) range from darkto lighted conditions, a threshold for operating the latch circuits,should be set for detecting a Type 328 lamp filament resistance(temperature) of 20 ohms or more for the lamp to be considered as beinghot (lighted). This is, of course, a nominal figure and will vary withthe type of lamp employed.

DESCRIPTION OF OPERATION Initial conditions chosen for the followingdescription of operation are: lamp 11,, ON, filament resistance hot(400); lamp ll, OFF, filament resistance cold (50); and lamp 11,,, ON,filament resistance also hot. These conditions result from the arbitraryassumption that the assignor 2 has designated: that lamp 1],, report aG0 condition for operational circuit 1,; that lamp 11,,, report a NOCOcondition for circuit 1 and lamp 1],, report a G0 condition for circuit1,. These conditions have been transmitted to the lamp matrix by way ofdata channel 80 and the time-shared writing circuits which will bediscussed in greater detail below.

Interrogation and Lamp Status Maintenance Normally all the diodes 12 and32 are reverse biased by V applied to location conductors l3,-13,,through the associated resistor 21,21,,, and by ground applied to thefunction conductor 14,-13 through resistor 34 and the seriescombinations 31,, 32,-31,,, 32,,. In operation, the distributor 25applies a negative pulse to the base of transistor 20, which conductsand causes a ground potential, pulse 0, FIG. 2, to be applied toconductor 13,. At this time, ground potential exists across each of thelamps of LOCATION 01. Immediately after the application of pulse 0,, thetiming circuits 70 apply pulse 1, to transistor 30 which, in turn,momentarily conducts to apply a similar, but negative pulse to conductor33. The voltage dividers established along each function conductor(elements 30, 32, 31, 14, 12, 11 and 20,) between potentials V andground cause a negative excursion at the junctions between diodes 12 andresistors 31. These negative excursions are applied to the respectivelatch circuits 40 for detection.

Attention is invited to latch circuit 40,, which receives a negativeexcursion from function conductor 14 In the absence of any writingsignals (discussed below), this negative potential change is coupled tothe base of transistor 41 which conducts (transistor 50 is normallyconducting) and, in turn, causes transistor 42 to conduct and feed backa negative potential from source V through resistor 43 to the base oftransistor 41 latching these transistors. At this time substantially Vvolts are applied across lamp 1],, and diode 12,,, ground from pulse 0,being applied to conductor 13, and V volts being applied to conductor14,, through transistor 42. This same action takes place for hot lamp11,, and latch circuit 40,; however, lamp 11, and latch circuit 40,operate differently from that just described. The negative excursion dueto the cold (low resistance) filament of lamp 11,, is slight compared tothat of a hot lamp, and therefore the slight negative excursion duringpulse 1', is ignored due to the dimensioning of the components of thelatch circuits, that is, the 50 pulse is below the operating thresholdof latch circuit 40,. Since latch circuit 40 is incapable of operatingupon such slight excursions, no sustaining circuit to the time sharingdriver 20, is completed through the latching transistor of circuit 40,;lamp 11, stays off.

Just prior to the end of the first time position, the timing circuitsmomentarily condition transistor 50 nonconductive to place a resettingpotential (FIG. 3, pulse r,) to diodes 46 of latch circuits 40, and 40,,to reset these circuits and condition the matrix for the application ofthe next pulse, pulse 0,, to conductor 13 (not shown) during the secondtime position.

Lamp Status Alteration (Writing) To alter the status of a lamp, the datachannel loads register 61 with the matrix location of the lamp inquestion and the decoder provides writing pulses to control operation ofthe appropriate latch circuits. For example, if operational circuit 1(assumed for the purposes of the present example to be associated withLOCATION 01) has its switch closed (GO) and the operational circuit 1(also assumed to be associated with LOCATION 01) has its switch opened(NO-GO), dark lamp 11,, is to be lighted and lighted lamp 11,,, is to bedarkened. Information for such action is loaded into the data inputcircuit 60 over the data channel 80 and subchannel 82. Under the controlof timing circuits 70, and at the beginning of the first time position(pulse 6,) the decoder applies pulse 6,F2, and 9,Fn,, to latch circuits40 and 40, respectively, to write a binary 1" (ON condition) intoLOCATION 01, FUNCTION 02 and a binary 0" (OFF condition) into LOCATION01, FUNCTION 0n. Such pulses override any control provided by thesampling pulses and operate, or inhibit operation of, their respectivelatch circuits. Therefore, in the present example lamp 11,, receivesfull drive power over the aforementioned type of powering circuitthrough latch circuit 40 and the possibility of such a circuit beingmaintained for lamp 11,,, is removed.

It is evident from FIG. 4 and the above description that the thermalinertia of an OFF lamp is easily overcome and the lamp lighted byoverdriving the lamp in its low resistance state with an initially highcurrent. Also, the thermal inertia permits the sustaining of a lightcondition for driving only during a portion of the time position afterinterrogation. By the same token, a lighted lamp may be extinguished andconditioned to a filament resistance value that is easily detectable asa cold lamp (below the detection threshold of the latch circuit) duringone or a few time positions. From the cooling characteristics of typicallamps it can be shown that for a large number of time positions perframe only one or two control pulses are required to write a 0", whilefor a small number of time positions per frame require a larger numberof control pulses to insure that a lamp is turned off. Therefore, eithereach lamp of a particular system should be quickly cooled with respectto time position recurrence or the decoder and time circuits must beconstructed to supply sufficient number of write 0" pulses (e.g. 0,Fn toinsure lamp turn off.

What is claimed is:

1. In a system having a plurality of operational circuits which haveGO/NO-GO operational conditions and which provide information signalsindicative of changes in said operational conditions, apparatus forreporting operational conditions to a plurality of locations on atime-sharing basis, said apparatus comprising:

a matrix including firsbcoordinate conductors corresponding to separateones of said plurality of lamps divided into separately located lampgroups, each of said lamps corresponding to a separate operationalcircuit and having a filament resistance of at least a predeterminedvalue when lighted, and each said group of lamps being separatelyconnected to the first coordinate conductor which is individual to saidgroup and being connected to a plurality of said second coordinateconductors in common with the lamps from other lamp groups;

means connected to said first coordinate conductors of said matrix forscanning the last-mentioned conductors to partially establish circuitsfor the lamps of each said group during unique recurring time positionsassigned to said groups;

interrogation means connected in common to said second coordinateconductors;

a plurality of interrogation circuits extending separately over saidsecond coordinate conductors and completed by said interrogation meansduring each of said time positions, for developing separately on eachsaid second coordinate conductor, a test signal which is indicative ofthe resistance value of the lamp being interrogated;

a plurality of bistable latching circuits each individually connected toa corresponding second coordinate conductor for detecting the testsignal thereon, said bistable circuits being operated during said timepositions to complete, under the control of said separate test signals,powering circuits for those lamps connected to said corresponding secondcoordinate conductor which exhibit a filament resistance of at leastsaid predetermined value;

and data input means connected to said plurality of bistable circuitsfor operating, or inhibiting the operation of, selected ones of saidbistable circuits during said time positions in response to saidinformation signals, thereby to alter the status of said matrix at willirrespective of said test signals.

2. In a system having a plurality of operational circuits which haveGO/NO-GO operational conditions and which provide information signalsindicative of changes in said operational conditions, apparatus forreporting operational conditions to a plurality of locations on atime-sharing basis, said apparatus comprising:

a matrix including first coordinate conductors corresponding to separateones of said plurality of locations, second coordinate conductors, and aplurality of lamps divided into separately located lamp groups, each ofsaid lamps corresponding to a separate operational circuit and having afilament resistance of at least a predetermined value when li hted, andeach said group of lamps being separate y connected to the firscoordinate conductor which is individual to said group and beingconnected to a plurality of said second coordinate conductors in commonwith the lamps from other lamp groups;

means connected to said first coordinate conductors of said matrix forscanning the last-mentioned conductors to partially establish circuitsfor the lamps of each said group during unique recurring time positionsassigned to said groups;

interrogation means connected in common to said second coordinateconductors;

a plurality of interrogation circuits extending separately over saidsecond coordinate conductors and completed by said interrogation meansduring each of said time positions for developing separately on eachsaid second coordinate conductor, a test signal which is indicative ofthe resistance value of the lamp being interrogated;

a plurality of bistable self-latching circuits each individuallyconnected to a corresponding second coordinate conductor for detectingthe test signal thereon, said bistable circuits being operated duringsaid time positions to complete, under the control of said separate testsignals, powering circuits for those lamps connected to saidcorresponding second coordinate conductor which exhibit a filamentresistance of at least said predetermined value;

timing means synchronized with said scanning means and connected to saidinterrogation means and to said bistable circuits, said timing meansactivating said interrogation means shortly after the beginning of eachsaid time position and resetting said bistable circuits shortly beforethe end of each said time position;

and data input means connected to said plurality of bistable circuitsfor operating, or inhibiting the operation of, selected ones of saidbistable circuits during said time positions in response to saidinformation signals, thereby to alter the status of said matrix at willirrespective of said test signals.

1. In a system having a plurality of operational circuits which haveGO/NO-GO operational conditions and which provide information signalsindicative of changes in said operational conditions, apparatus forreporting operational conditions to a plurality of locations on atime-sharing basis, said apparatus comprising: a matrix includingfirst-coordinate conductors corresponding to separate ones of saidplurality of lamps divided into separately located lamp groups, each ofsaid lamps corresponding to a separate operaTional circuit and having afilament resistance of at least a predetermined value when lighted, andeach said group of lamps being separately connected to the firstcoordinate conductor which is individual to said group and beingconnected to a plurality of said second coordinate conductors in commonwith the lamps from other lamp groups; means connected to said firstcoordinate conductors of said matrix for scanning the last-mentionedconductors to partially establish circuits for the lamps of each saidgroup during unique recurring time positions assigned to said groups;interrogation means connected in common to said second coordinateconductors; a plurality of interrogation circuits extending separatelyover said second coordinate conductors and completed by saidinterrogation means during each of said time positions, for developingseparately on each said second coordinate conductor, a test signal whichis indicative of the resistance value of the lamp being interrogated; aplurality of bistable latching circuits each individually connected to acorresponding second coordinate conductor for detecting the test signalthereon, said bistable circuits being operated during said timepositions to complete, under the control of said separate test signals,powering circuits for those lamps connected to said corresponding secondcoordinate conductor which exhibit a filament resistance of at leastsaid predetermined value; and data input means connected to saidplurality of bistable circuits for operating, or inhibiting theoperation of, selected ones of said bistable circuits during said timepositions in response to said information signals, thereby to alter thestatus of said matrix at will irrespective of said test signals.
 2. In asystem having a plurality of operational circuits which have GO/NO-GOoperational conditions and which provide information signals indicativeof changes in said operational conditions, apparatus for reportingoperational conditions to a plurality of locations on a time-sharingbasis, said apparatus comprising: a matrix including first coordinateconductors corresponding to separate ones of said plurality oflocations, second coordinate conductors, and a plurality of lampsdivided into separately located lamp groups, each of said lampscorresponding to a separate operational circuit and having a filamentresistance of at least a predetermined value when lighted, and each saidgroup of lamps being separately connected to the first coordinateconductor which is individual to said group and being connected to aplurality of said second coordinate conductors in common with the lampsfrom other lamp groups; means connected to said first coordinateconductors of said matrix for scanning the last-mentioned conductors topartially establish circuits for the lamps of each said group duringunique recurring time positions assigned to said groups; interrogationmeans connected in common to said second coordinate conductors; aplurality of interrogation circuits extending separately over saidsecond coordinate conductors and completed by said interrogation meansduring each of said time positions for developing separately on eachsaid second coordinate conductor, a test signal which is indicative ofthe resistance value of the lamp being interrogated; a plurality ofbistable self-latching circuits each individually connected to acorresponding second coordinate conductor for detecting the test signalthereon, said bistable circuits being operated during said timepositions to complete, under the control of said separate test signals,powering circuits for those lamps connected to said corresponding secondcoordinate conductor which exhibit a filament resistance of at leastsaid predetermined value; timing means synchronized with said scanningmeans and connected to said interrogation means and to said bistablecircuits, said timing means activating said interrogation means shortlyafter the beginning Of each said time position and resetting saidbistable circuits shortly before the end of each said time position; anddata input means connected to said plurality of bistable circuits foroperating, or inhibiting the operation of, selected ones of saidbistable circuits during said time positions in response to saidinformation signals, thereby to alter the status of said matrix at willirrespective of said test signals.